Aqueous treatment agents of the copolymer, which is a fluorine-containing copolymer comprising repeating units derived from a fluoroacrylate having a long chain Rf group having at least 8 carbon atoms and further comprising an amino group-containing component polymerizable compound, is already known as a treatment agent for a fiber (for example, U.S. Pat. No. 4,147,851). In the case of the fiber, the fiber has easy penetration of treatment agent in comparison with substrates having microstructure such as stones, and if the stability as the treatment agent is kept, practical use is possible and solubility in water is not required. JP-A-8-225620 discloses a method of improving a polymer containing long chain Rf having at least 6 carbon atoms by means of isocyanate crosslink. This proposed method is essentially different from the present invention of improving penetration into minute porous substrate. JP-T-2002-524645 proposes a method of treating asphalt materials by using a copolymer containing a long chain Rf group. In this treatment agent, substrates are limited to the substrate having easy penetration of the treatment agent, which is an asphalt material. The addition of a water-soluble auxiliary solvent has been practically needed in order to penetrate, into of fine pores, an aqueous solution treatment agent of a copolymer containing a long chain Rf group.
Described below are the environmental problems raised by perfluorooctanoic acid (PFOA).
The results of the latest researches [a report of the Environmental Protection Agency (EPA), “PRELIMINARY RISK ASSESSMENT OF THE DEVELOPMENTAL TOXICITY ASSOCIATED WITH EXPOSURE TO PERFLUOROOCTANOIC ACID AND ITS SALTS” (http://www.epa.gov/opptintr/pfoa/pfoara.pdf)] have taught that PFOA (perfluorooctanoic acid), one of long chain fluoroalkyl compounds, is proved to have a danger to burden the environment. Under such a situation, EPA announced on Apr. 14, 2003 that the scientific investigation on PFOA should be more intensively executed.
On the other hand, the Federal Register (FR Vol. 68, No. 73/Apr. 16, 2003 [FRL-7303-8], http://www.epa.gov/opptintr/pfoa/pfoafr.pdf), EPA Environmental News FOR RELEASE: MONDAY Apr. 14, 2003 EPA INTENSIFIES SCIENTIFIC INVESTIGATION OF A CHEMICAL PROCESSING AID (http://www.epa.gov/opptintr/pfoa/pfoaprs.pdf) and EPA OPPT FACT SHEET Apr. 14, 2003 (http://www.epa.gov/opptintr/pfoa/pfoafacts.pdf) have published that telomers have a possibility to produce PFOA when decomposed or metabolized (herein, the telomer means a long chain fluoroalkyl group), and also that telomers have been widely used in foam fire extinguishers, care products, washing materials, carpets, textiles, paper, leather, etc., in order to impart water and oil repellency and soil resistance to them.
A conventionally mentioned product comprising a fluorine-containing copolymer containing Rf group having at least 8 carbon atoms increasingly has a problem of containing PFOA and PFOA-like material having bioaccumulation characteristics.
Accordingly, the prompt convert to a fluorine-containing polymer comprising a fluoroacrylate having at most 6 carbon atoms in short-chain Rf group, and the development of a fluorine-containing polymer having the improved affinity with other materials and skin are required.    Patent Document 1: U.S. Pat. No. 4,147,851    Patent Document 2: JP-A-8-225620    Patent Document 3: JP-T-2002-524645